In a conventional chewing gum manufacturing process, a double arm Sigma blade mixer is used to mix chewing gum ingredients. Gum base, bulking agents such as sugar or sorbitol for sugarless gum, liquids such as syrup or liquid sorbitol, softeners such as glycerin and lecithin, and flavors are mixed about 5-20 minutes to manufacture the gum.
This conventional gum making process, using batch mixing, involves an open mixer that allows flavor components to be lost by volatilization or degradation, particularly during the relatively long mixing times required to incorporate the flavor into the chewing gum composition. This is true even though flavor is typically added as the last ingredient, and mixed at the minimum temperatures needed for mixing. While most gum flavors, like spearmint, peppermint, cinnamon and wintergreen are subject to volatilization, fruit flavors are especially susceptible to this problem.
In conventional gum manufacturing, the time at which flavors are added effects the flavor release during chewing. For example, a gum mixed with flavor for extended time periods, longer than 5 minutes, will have a slow flavor release. However, this is not practical in the batch process because a mixing time of 10 or 15 minutes causes much of the flavor to be lost. Thus, optimized flavor perception in the final gum product may have to be sacrificed for the sake of keeping the level of flavor volatilization and degradation to a minimum.
Conventionally, chewing gum base and chewing gum products have been manufactured using separate mixers, different mixing technologies and, often, at different factories. One reason for this is that the optimum conditions for manufacturing gum base, and for manufacturing chewing gum from gum base and other ingredients such as sweeteners and flavors, are so different that it has been impractical to integrate both tasks. Chewing gum base manufacture, on the one hand, involves the dispersive (often high shear) mixing of difficult-to-blend ingredients such as elastomer, filler, elastomer plasticizer, base softeners/emulsifiers and, sometimes wax, and typically requires long mixing times. Chewing gum product manufacture, on the other hand, involves combining the gum base with more delicate ingredients such as product softeners, bulk sweeteners, high intensity sweeteners and flavoring agents using distributive (generally lower shear) mixing, for shorter periods.
In order to improve the efficiency of gum base and gum product manufacture, there has been a trend toward the continuous manufacture of chewing gum bases and products. U.S. Pat. No. 3,995,064, issued to Ehrgott et al., discloses the continuous manufacture of gum base using a sequence of mixers or a single variable mixer. U.S. Pat. No. 4,459,311, issued to DeTora et al., also discloses the continuous manufacture of gum base using a sequence of mixers. Other continuous gum base manufacturing processes are disclosed in European Patent Publication No. 0,273,809 (General Foods France) and in French Patent Publication No. 2,635,441 (General Foods France).
U.S. Pat. No. 5,045,325, issued to Lesko et al., and U.S. Pat. No. 4,555,407, issued to Kramer et al., disclose processes for the continuous production of chewing gum products. In each case, however, the gum base is initially prepared separately and is simply added into the process. U.S. Pat. No. 4,968,511, issued to D'Amelia et al., discloses a chewing gum product containing certain vinyl polymers which can be produced in a direct one-step process not requiring separate manufacture of gum base. However, the disclosure focuses on batch mixing processes not having the efficiency and product consistency achieved with continuous mixing. Also, the single-step processes are limited to chewing gums containing unconventional bases which lack elastomers and other critical ingredients.
There is a need for a continuous chewing gum manufacturing process that yields a gum with controlled flavor release. Even more beneficial would be an integrated continuous manufacturing process having the ability to combine chewing gum base ingredients and other chewing gum ingredients in a single continuous mixer in a way that reduces flavor loss and yields gum with controlled flavor release characteristics.